1. Field of the Invention
The present invention relates to a layout structure of a fuel injection device for an engine mounted on a motorcycle. More particularly, to an improvement of a fuel injection type engine which includes a cylinder head in which an intake port is formed. A throttle body has an intake passage leading to the intake port in a body thereof and a throttle valve is arranged which is capable of controlling a flow area of the intake passage in the body such that the throttle valve is operable to be opened and closed. A fuel injection valve injects fuel toward the intake port.
2. Description of Background Art
In general, with respect to a vehicle-use engine, there has been proposed a vehicle-use engine which adopts a fuel injection device in place of a carburetor as the fuel supply means from a viewpoint of the enhancement of the accuracy of controlling the fuel, the purification of an exhaust gas, the low fuel consumption or the like. When such a fuel injection type engine is mounted on a motorcycle and the fuel injection device is mounted on a cylinder of the engine, a total height of the engine is increased. Hence, there arises a drawback in that a total height of the motorcycle is increased.
To solve such a drawback, for example, there has been proposed a technique wherein a cylinder of an engine mounted on a motorcycle is inclined toward a vehicle front side and a valve shaft of a fuel injection device is arranged substantially parallel to a cylinder shaft. See, Japanese Patent Publication 2995198.
Here, when the motorcycle is an offroad vehicle, the motorcycle is required to satisfy a more speedy operation to cope with the manipulation demands of a rider. Hence, it is desirable to miniaturize the vehicle as a whole. Thus, the application of the layout structure of the fuel injection device described in Japanese Patent Publication 2995198 to such an offroad vehicle is considered.
In addition, there has been disclosed a fuel injection type engine which mounts a fuel injection valve for injecting fuel toward an intake port of a cylinder head on the cylinder head. See, for example, Japanese Unexamined Patent Publication Hei 11(1999)-245894.
However, in the conventional construction, a valve shaft is provided substantially parallel to the cylinder of the engine. Hence, a large space is formed between a main frame which constitutes a vehicle body frame and the engine. In addition, at the same time, a large space is formed between the fuel injection device and the main frame.
Accordingly, even when such a construction is applied to the offroad vehicle, it is difficult to achieve the further enhancement of the layout efficiency thus giving rise to drawbacks including a drawback that the achievement of the miniaturization of the vehicle is difficult.